Sooner or later, CMOS Scaling will come to an end. What do we do next? A number of very different switches have been proposed as replacements, some of which in fact do not even use electron charge as the state variable.Instead, these switches pass tokens in the spin, excitonic, photonic, magnetic, quantum, or heat domains. The emergent physical behaviors and idiosyncrasies of these novel switches can complement the execution of specific task algorithms or workloads, and improve overall thru-put in high performance computing. This talk will describe potential CMOS replacements, focusing upon their preferred circuits and architectures. The discussion highlights the output of SRC’s NRI Architectures Study, supported in part with NSF and NIST funding.